1. Field of the Invention
The present invention relates to a cooling mechanism of an optical modulator attached to a light-incident end of a prism, an optical modulator attachment unit for attaching the optical modulator on a light-incident end of the prism and a projector having the same.
2. Description of Related Art
Conventionally, a projector including three optical modulators for modulating a plurality of colors of light in accordance with image information, a cross dichroic prism for combining the color light modulated by the three optical modulator, and a projection lens for enlarging and projecting the light combined by the prism has been used.
Such projectors have been widely used for multimedia presentation in a meeting, scientific society, exhibition etc., and size reduction thereof has been strongly desired since such projectors are brought to other locations as necessary and is brought to other places for storing.
In recent years, in order to reduce size and simplify structure thereof, an arrangement for attaching the optical modulator to a light-incident end of the prism has come to be used. For instance, according to an arrangement shown in Japanese Patent Laid-Open Publication No. Hei 2000-221588, three optical modulators are respectively held by a holding frame and a stick member is inserted to four comers of the holding frame with a distal end thereof being fixed to the light-incident end of the cross dichroic prism by an adhesive, thereby attaching the optical modulator to the cross dichroic prism.
According to another arrangement shown in International Publication No. WO98/27453, an optical modulator held by a holding frame is attached to a light-incident end of the prism through a frame body and a wedge-shaped spacer. A guide for guiding the wedge-shaped spacer is formed on the holding frame.
A polarizer for polarizing the light modulated by the optical modulator is provided between the optical modulator and the light-incident end of the prism. The polarizer is directly adhered to the light-incident end of the prism by an adhesive etc.
The polarizer is formed by attaching a polarizing film to a glass substrate. The polarizing film can be deteriorated on account of heat generated by the light passing the prism and the optical modulator after long use and projected image quality can be deteriorated in accordance therewith. On the other hand, since the optical modulator is also weak in heat, the optical modulator has to be cooled by cooling air. Accordingly, in order to efficiently cool the polarizer and the optical modulator, there is an idea for feeding the cooling air between the light-incident end of the prism and the optical modulator.
However, only a narrow gap is formed between the prism and the optical modulator in accordance with size reduction, even when cooling air is sent from lower side of the prism by, for instance, a suction fan etc., only a little air enters between the prism and the optical modulator, so that efficient cooling of the polarizer and the optical modulator is difficult.
Further, an axial fan is used as a suction fan disposed on the lower side of the prism. Since the cooling air exhausted from the axial fan flows in spiral, the cooling air is blown to the surface of the optical modulator obliquely upward, so that it is difficult to uniformly cool the surface of the optical modulator.
An object of the present invention is to provide a cooling mechanism of an optical modulator capable of efficiently cooling a polarizer, an optical modulator etc., an optical modulator attachment unit and a projector having the cooling mechanism.
A cooling mechanism of optical modulator according to the present invention is for an optical modulator plurally attached to a light-incident end of a prism for modulating a plurality of color lights in accordance with image information and for emitting the modulated light to the light-incident end of the prism, the cooling mechanism including: a base member attached to the light-incident end of the prism; and a support member attached to the base member for supporting the optical modulator, the support member including a pair of components disposed parallel to a cooling air flow channel formed between the light-incident end of the prism and the optical modulator and for supporting a neighborhood of an end of the optical modulator.
The plurality of optical modulators may be, for instance, three optical modulators for modulating red, green and blue light beams, which may be attached to the light-incident end of the prism by, for instance, an arrangement where the gap between the light-incident end of the prism and the optical modulator is likely to become small such as attaching the optical modulator to the light-incident end of the prism by a screw or a spacer.
According to the present invention, since the support member for supporting the optical modulator is formed by a pair of components disposed parallel to the cooling air flow channel formed between the light-incident end of the prism and the optical modulator for supporting the neighborhood of the end of the optical modulator, the gap between the light-incident end of the prism and the optical modulator facing the cooling air flow channel can be enlarged, so that cooling air sufficient for cooling the polarizer and the optical modulator can be flowed in the direction of the cooling air flow channel. Accordingly, the polarizer and the optical modulator can be efficiently cooled.
In the cooling mechanism according to the present invention, a polarizer may preferably be provided on a light-emitting side of the optical modulator, a polarizer fixing plate for holding and fixing the polarizer may preferably interposed between the base member and the fixing plate; and the polarizer fixing plate may preferably hold and fix the polarizer being spaced apart from the light-incident end of the prism with a predetermined gap therebetween.
Accordingly, sufficient cooling air can be flowed not only between the polarizer and the optical modulator but also between the polarizer and the light-incident end of the prism, so that both sides of the polarizer can be efficiently cooled.
In the cooling mechanism according to the present invention, the support member may preferably include a fixing plate attached to the base member, an optical modulator fixing plate attached to the optical modulator and a spacer interposed between the fixing plate and the optical modulator fixing plate, the fixing plate, the optical modulator fixing plate and the spacer being disposed around the end of the optical modulator approximately in parallel.
Accordingly, since the gap between the light-incident end of the prism and the optical modulator facing the cooling air flow channel can be enlarged as mentioned above, the cooling efficiency can be enhanced, and the focus and alignment of the optical modulator can be adjusted only by changing the insertion amount of the pair of spacers inserted to the end.
In the cooling mechanism according to the present invention, a slanted surface for guiding the spacer may preferably be formed on the optical modulator fixing plate.
Accordingly, since the insertion amount of the spacer can be adjusted along the slanted surface, the focus and alignment adjustment of the optical modulator can be facilitated.
In the cooling mechanism according to the present invention, a cooling fan for cooling the optical modulator and a wind guide provided between the cooling fan and the optical modulator for introducing the cooling air from the cooling fan in a predetermined direction may preferably be provided, the wind guide including a first guide plate for directing the cooling air toward between the light-incident end of the prism and the optical modulator.
By introducing the cooling air from the cooling fan toward between the light-incident end of the prism and the optical modulator by the first guide plate, the cooling air from the cooling fan can be securely guided to the gap between the light-incident end of the prism and the optical modulator, so that the polarizer and the optical modulator can be further efficiently cooled.
In the cooling mechanism according to the present invention, the wind guide may preferably include a second guide plate extending in a direction orthogonal with an image formation area of the optical modulator.
The cooling fan disposed below the prism is ordinarily an axial flow fan. Since the air discharged from the axial flow fan flows in spiral, the cooling air blows the surface of the optical modulator obliquely upward, so that it is difficult to send the cooling air toward, for instance, corners of the optical modulator.
However, when the second guide plate is provided, turbulence can be generated to the air from the cooling fan by the second guide plate, so that the entire image formation area of the optical modulator can be uniformly cooled. Further, by disposing the second guide plate on an upstream side of the spiral air discharged from the cooling fan relative to the horizontal center of the image formation area, the entire image formation area of the optical modulator can be more uniformly and efficiently cooled.
In the cooling mechanism according to the present invention, the wind guide may preferably be provided in accordance with the number of the optical modulator, and the plurality of wind guides may preferably be integrally formed.
Accordingly, the wind guide can be more easily formed as compared to an arrangement where the wind guide is independently provided for each optical modulator, so that the wind guide can be easily assembled to the optical modulator.
The present invention not only can be applied to the cooling mechanism of the optical modulator, but also can be applied as a projector having the cooling mechanism of the optical modulator where the same functions and effects can be obtained.
An optical modulator attachment unit according to the present invention is for attaching an optical modulator to a light-incident end of a prism, the attachment unit including: a holding frame for holding the optical modulator; a base member attached to the light-incident end of the prism; and a pair of support members attached between the base member and the holding frame, the support member including a pair of components for supporting a neighborhood of an end of the optical modulator.
The plurality of optical modulators may be, for instance, three optical modulators for modulating red, green and blue light beams.
According to the present invention, since the support member is provided between the base member for supporting the optical modulator and the holding frame, the gap between the light-incident end of the prism and the optical modulator can be enlarged, so that cooling air sufficient for cooling the polarizer, the optical modulator etc. can be flowed. Accordingly, the polarizer and the optical modulator can be efficiently cooled.
In the optical modulator attachment unit according to the present invention, a polarizer may preferably be provided on the light-emitting side of the optical modulator, a polarizer fixing plate for holding and fixing the polarizer on the light-emitting side may preferably interposed between the base member and the optical modulator; and the polarizer fixing plate may preferably hold and fix the polarizer being spaced apart from the light-incident end of the prism with a predetermined gap therebetween.
Accordingly, sufficient cooling air can be flowed not only between the polarizer and the optical modulator but also between the polarizer and the light-incident end of the prism, so that both sides of the polarizer can be efficiently cooled.
In the optical modulator attachment unit according to the present invention, the support member may preferably include a fixing plate attached to the base member, an optical modulator fixing plate attached to the optical modulator and a spacer interposed between the fixing plate and the optical modulator fixing plate.
Accordingly, since the gap between the light-incident end of the prism and the optical modulator can be enlarged, the cooling efficiency can be enhanced, and the focus and alignment of the optical modulator can be adjusted only by changing the insertion amount of the pair of spacers.
In the optical modulator attachment unit according to the present invention, a slanted surface for guiding the spacer may preferably be formed on the optical modulator fixing plate.
Accordingly, since the insertion amount of the spacer can be adjusted along the slanted surface, the focus and alignment adjustment of the optical modulator can be facilitated. Further, though the structure of the holding frame can be complicated for forming a guide on the holding frame for guiding the wedge-shaped spacer in the arrangement disclosed in the International Publication No. WO98/27453, since the guide for guiding the spacer is not necessarily formed on the holding frame in the above arrangement, the production cost can be reduced.
The present invention not only can be applied to the optical modulator attachment unit, but also can be applied as a projector having the optical modulator attachment unit for obtaining the same functions and effects.
In the optical modulator attachment unit according to the present invention, a cooling fan for cooling the optical modulator and a wind guide provided between the cooling fan and the optical modulator for introducing the cooling air from the cooling fan in a predetermined direction may preferably be provided, the wind guide including a first guide plate for directing the cooling air toward between the light-incident end of the prism and the optical modulator.
By introducing the cooling air from the cooling fan toward between the light-incident end of the prism and the optical modulator by the first guide plate, the cooling air from the cooling fan can be securely guided to the gap between the light-incident end of the prism and the optical modulator, so that the polarizer and the optical modulator can be further efficiently cooled.
In the optical modulator attachment unit according to the present invention, the wind guide may preferably include a second guide plate extending in a direction orthogonal with an image formation area of the optical modulator.
The cooling fan disposed below the prism is ordinarily an axial flow fan. Since the air discharged from the axial flow fan flows in spiral, the cooling air blows the surface of the optical modulator obliquely upward, so that it is difficult to send the cooling air toward, for instance, corners of the optical modulator.
However, when the second guide plate is provided, turbulence can be generated to the air from the cooling fan by the second guide plate, the entire image formation area of the optical modulator can be uniformly cooled. Further, by disposing the second guide plate on an upstream side of the spiral air discharged from the cooling fan relative to the horizontal center of the image formation area, the entire image formation area of the optical modulator can be more uniformly and efficiently cooled.
In the optical modulator attachment unit according to the present invention, the wind guide may preferably be provided in accordance with the number of the optical modulator, and the plurality of wind guides may preferably be integrally formed.
Accordingly, the wind guide can be more easily formed as compared to an arrangement where the wind guide is independently provided in accordance with respective optical modulator, so that the wind guide can be easily assembled to the optical modulator.